It is known to obtain effective bulletproof protection thanks to structures which are realized by means of suitable combinations of interwoven fibers able to absorb and disperse the stopping force and penetration of the bullets by means of plastic deformation (elongation) of said fibers.
The number of superimposed layers determines the protective capacity of the structure as a whole, which is categorized for example in protection classes referred to as NIJ (United States) or SK (Germany).
These structures are generally formed by several layers of fibers which are interwoven or woven, in particular aramid fibers, and glued onto polyethylene films, in a final configuration which is in any case flexible. In general, these structures are made of high tenacity fibers, such as aramid fibers.
An aramid fiber has in fact a high mechanical tensile strength so much so that, for the same weight, it is five times stronger than steel; moreover such aramid fiber has a high heat and flame resistance, such that it is particularly suitable for use as a reinforcing fiber for the construction of extreme sports equipment and components used in aircraft, boats and racing cars, as well as military helmets and some articles of safety work clothing.
One of the most widely known applications of high tenacity fibers can be found in bulletproof vests: their high strength is used to absorb, by means of plastic deformation, the kinetic energy of the bullets, reducing to the minimum the effects on the user wearing the vest, in particular the so-called impact traumas and consequent bruising, internal lesions or even localized fractures, which are caused by transfer to the user's body of the energy absorbed by the fibers, net of that dispersed due to the plastic deformation thereof.
Normally the fiber structures are able to provide effective protection against bullets from short arms and to a limited extent automatic arms up to caliber 7.65 or 9 Parabellum, corresponding to 0.357 and 0.44 Magnum pistols and a speed of up to about 500 m/s. This corresponds to a protection level IIIa of the United States NIJ standard.
For protection against larger caliber bullets it is known to add to these fiber structures at least one semi-rigid or rigid ballistic panel able to break up the faster bullets (more than 700 m/s) into smaller parts which can be more easily stopped by the underlying fiber structure, owing to the reduction of their energy (divided up among the different fragmented parts). It is emphasized that the impact of bullets on this ballistic panel may in any case result in impact traumas.
In particular, these ballistic panels may be made of metallic materials and more often of so-called ballistic ceramic, namely a high-strength aluminum oxide able to break up the bullets and thus divide them into fragments. For this reason, these ballistic panels are made with fairly large thicknesses and in particular with thicknesses of between 5 and 12 mm, and preferably between 7 and 10 mm.
A bulletproof protection structure for calibers greater than 0.357 and 0.44 Magnum, namely higher than a level IIIa of the United States NIJ standard, realized according to the prior art is shown in schematic form in FIG. 1, denoted overall by 10.
A bulletproof protection structure 10 may for example be used for armoring vehicles and tanks.
The bulletproof protection structure 10, in the example shown purely by way of example, has a substantially rectangular form and comprises a fiber base 11 made for example using high tenacity fibers, which are for example interwoven, also referred to as ballistic fabric.
Such a bulletproof protection structure 10 also comprises a plurality of ballistic panels 12 associated with the fiber base 11, for example by gluing. In particular, the ballistic panels 12 may be made of ballistic ceramic.
As shown in the figure, the ballistic panels 12 may be suitably spaced so as to define, between two adjacent panels, at least a portion 13 of the fiber base 11 which is free from them and therefore allows folding over of the bulletproof protection structure 10 along folding lines indicated by 14.
The bulletproof protection structure 10 shown in FIG. 1 is thus able to cover a prism-shaped object, in particular with a square base, the ballistic panels 12 shown in the figure having the same sizes.
It is obviously possible to make the bulletproof protection structure 10 using ballistic panels 12 of different sizes, in particular able to follow the forms of the object to be covered and protected, as uniformly as possible. This complicates the protection of surfaces which are irregular and makes protection practically impossible in the case of rounded forms, such as cylindrical towers, leading to the imposition of square forms with corner edges. Moreover, the portions 13 devoid of the ballistic panels 12 are less protected and in particular may be penetrated by bullets of caliber greater than 0.357 and 0.44 Magnum, namely higher than a level IIIa of the United States NIJ standard. In these portions 13, in fact, the bulletproof protection is provided only by the fiber base 11.
This problem becomes even greater in the case of personal protective clothing which can be worn by a user, such as a bulletproof vest or jacket, in particular suitable for effective bulletproof protection against calibers greater than 0.357 and 0.44 Magnum, namely higher than a level IIIa of the United States NIJ standard.
The bulletproof vest is a garment, generally in the form of a waistcoat or jersey, which is used by armies and armed forces and is intended to protect the person wearing it against shots from firearms or shrapnel produced by explosives (in this latter case the vest is more commonly referred to as a “flak jacket”), said garment retaining the bullet or shrapnel inside it. This type of garment is also used by security staff, for example working at banks or responsible for the transportation of valuables.
Generally speaking a bulletproof vest is formed by an outer containment element, conveniently made of ballistic fabric, and one or more internal ballistic panels, for example made of ballistic ceramic.
These ballistic panels are in particular used as shields and are therefore normally positioned in front of the chest of the person and at the rear over the back and, in some cases, lower down, in the waist region around the right-hand and left-hand flanks, so as to ensure protection for the vital organs of the user wearing the jacket.
An example of a bulletproof vest, denoted overall by 15, is illustrated in schematic form in FIGS. 2A, 2B and 2C in a front view, view from above and cross-sectional view A-A, respectively.
The bulletproof vest 15 comprises a ballistic fabric portion 16, in particular made of high tenacity fibers, which are for example interwoven, and usually inserted inside a containment lining 17.
The bulletproof vest 15 shown in FIGS. 2A-2C is of the type suitable for providing bulletproof protection for calibers greater than 0.357 and 0.44 Magnum, namely higher than a level IIIa of the United States NIJ standard, and therefore comprises at least one ballistic panels 18 associated with the ballistic fabric portion 16, for example by means of gluing, and positioned over the chest of a user wearing the vest. It is also possible to envisage providing the containment lining 17 with a suitable pocket for inserting the ballistic panel 18.
It is also possible to provide the bulletproof vest 15 with further ballistic panels 19A and 19B which have smaller sizes than those of the ballistic panel 18 and are positioned symmetrically along the sides of this ballistic panel 18 on the lateral flanks of the vest, in the waist region of the user wearing it. The ballistic panels 19A and 19B may be also associated with the ballistic fabric portion 16 by gluing or inserted inside special pockets in the containment lining 17.
It is further possible to design the bulletproof vest 15 so as to have a ballistic panel positioned also on the back of the user wearing it, with sizes similar to those of the ballistic panel 18, and also envisage further ballistic panels, in particular with even smaller sizes than those of the ballistic panels 19A and 19B, for example in the waist region of the user wearing the vest (said panels not being shown in figures).
Obviously these ballistic panels constitute an impediment to the movement of the human body, limiting the freedom of movement of the user wearing the bulletproof vest 15. The user wearing the bulletproof vest 15 is for example prevented from performing movements of the torso, including lateral, forwards or backwards movements.
Another drawback resulting from the ballistic panels is also the weight of the bulletproof vest 15, this being a very constraining factor when choosing the protection which is most suitable for the missions to be carried out. A bulletproof vest 15 able to ensure bulletproof protection for a level IV of the United States NIJ standard may weigh up to 10 kg.
The known solutions, although advantageous under many respects, therefore have various drawbacks, including the difficulty of adapting the bulletproof protection structures for calibers greater than 0.357 and 0.44 Magnum, namely higher than a level IIIa of the United States NIJ standard, to surfaces which are not flat. Moreover, in the case of garments for bulletproof protection of persons, the use of ballistic reinforcing panels results in the extreme rigidity and additional weight of the garments, which limit the comfort of the person wearing them; moreover they are able to provide effective protection only for an area substantially limited to the zones of the vital organs, such as the heart, owing to at least one ballistic panel positioned over the chest of the user wearing the vest.